"Well, listeria is the third leading cause of food-borne illness deaths in this country, so this is a very serious infection for the most vulnerable," said Paul Biedrzycki of the Milwaukee Health Department.

Pregnant women and those with immune deficiencies are especially at risk.

The state Department of Agriculture Trade and Consumer Protection considered the situation so serious that it issued a rare consumer alert because it believed that news of a massive food safety recall wasn't reaching enough people.

"This was an unusually large number of expanded recalls," said Raechelle Cline of the state Department of Agriculture Trade and Consumer Protection.

Garden Fresh supplies pre-packaged salads and dips to stores across the country under many popular brand names, such as Market Fresh, Archer Farms and its own Garden Fresh label.

But several hundred of their items were included in a series of recent federal recalls, so many, in fact, that the state warned consumers against eating any item produced there.

At this point, there have been no illnesses linked to the recalls.

WISN 12 News checked several local stores and found none of the recalled products still on the shelves, but health officials worry that consumers may have some in their homes, still posing a potential health risk.

Wainscott tried to ask the company about the situation but was referred its attorney, who confirmed that Garden Fresh has shut down its operations while investigators search for a cause of the listeria contamination -- impacting, according to the company's website, more than 100 employees.

While this investigation has temporarily put the brakes on this operation in Milwaukee, WISN 12 News has learned that it actually began with a discovery hundreds of miles away.

Sources told WISN 12 News that a routine inspection of food items on stores shelves in Michigan turned up the contamination in products which were traced back to the Milwaukee plant.

"Right now, my understanding is they haven't identified a reservoir source for this organism, but the plant has been shut down, which is very appropriate," Biedrzycki said.

But now, the investigation involves multiple agencies, with different responsibilities.

"It has been very confusing, even for us," Cline said.

While federal investigators, from both the FDA and U.S. Department of Agriculture, search for the source of the problem, state officials said they are left to watch and wait for answers.

"This is an investigation done by the FDA and the USDA, so it's really not under our purview at this point," Cline said.

"Is it frustrating that you can't, as an agency, step in and take some sort of action here?" Wainscott asked.

"It can be frustrating because it is such a serious pathogen, but we did what we could," Cline said.

The state is taking action where it can, ensuring that all recalled items are out of stores and not available to consumers.

"All of our inspectors have been advised to look for and make sure that these products are not on the shelves," Cline said.

A spokesman for the company told WISN 12 News Garden Fresh is cooperating in every way. The goal, he said, is to ensure safety, but right now, they don't know how long that might take.

TONIGHT -- 12 NEWS HAS LEARNED A MILWAUKEE FOOD PLANT IS CLOSED AFTER A SERIES OF MASSIVE RECALLS. A POTENTIALLY DEADLY BACTERIA SURFACED IN THEIR FOOD. 12 NEWS KENT WAINSCOTT WENT TO INVESTIGATE THE COMPANY AND THE SOURCE. HUNDREDS OF POPULAR FOOD ITEMS, PULLED FROM STORE SHELVES - THE CAUSE? SUSPECTED LISTERIA CONTAMINATION. PAUL BIEDRZYCKI / MILW HEALTH DEPT - HOW CONCERNING IS IT THAT THIS INVOLVES LISTERIA? - WELL LISTERIA IS THE THIRD LEADING CAUSE OF FOOD- BORN ILLNESS DEATHS IN THIS COUNTRY, SO THIS IS A VERY SERIOUS INFECTION, FOR THE MOST VULNERABLE. PREGNANT WOMEN AND THOSE WITH IMMUNE DEFICIENCIES ARE ESPECIALLY AT RISK. THE STATE DEPARTMENT OF AGRICULTURE TRADE AND CONSUMER PROTECTION CONSIDERED IT SO SERIOUS THAT IT ISSUED A RARE CONSUMER ALERT, BECAUSE IT BELIEVED THAT NEWS OF A MASSIVE FOOD SAFETY RECALL WASN'T REACHING ENOUGH PEOPLE. RAECHELLE CLINE / DATCP - THIS WAS AN UNUSUALLY LARGE NUMBER OF EXPANDED RECALLS. GARDEN FRESH SUPPLIES PRE-PACKAGED SALADS AND DIPS TO STORES ACROSS THE COUNTRY, UNDER MANY POPULAR BRAND NAMES - LIKE MARKET FRESH, ARCHER FARMS AND IT'S OWN GARDEN FRESH LABEL. BUT SEVERAL HUNDRED OF THEIR ITEMS WERE INCLUDED IN A SERIES OF RECENT FEDERAL RECALLS - SO MANY, IN FACT, THAT THE STATE WARNED CONSUMERS AGAINST EATING ANY ITEM PRODUCED HERE. AT THIS POINT, THERE HAVE BEEN NO ILLNESSES LINKED TO THE RECALLS. AND WE CHECKED SEVERAL LOCAL STORES AND FOUND NONE OF THE RECALLED PRODUCTS STILL ON THE SHELVES, BUT THE HEALTH OFFICIALS WORRY THAT CONSUMERS MAY HAVE SOME IN THEIR HOMES, STILL POSING A POTENTIAL HEALTH RISK. KENT NATS - MY NAME IS KENT WAINSCOTT, I'M FROM WISN-12... WE TRIED TO ASK THE COMPANY ABOUT THE SITUATION... KENT NATS - IS THERE ANYONE HERE WE CAN TALK TO ABOUT THIS RECALL? - NOT AT THIS TIME, NO. ...BUT WERE REFERRED THEIR ATTORNEY, WHO CONFIRMED THAT GARDEN FRESH HAS SHUT DOWN IT'S OPERATIONS WHILE INVESTIGATORS SEARCH FOR A CAUSE OF THE LISTERIA CONTAMINATION IMPACTING, ACCORDING TO THE COMPANY'S WEBSITE, MORE THAN 100 EMPLOYEES. KENT STANDUP - BUT WHILE THIS INVESTIGATION HAS TEMPORARILY PUT THE BRAKES ON THIS OPERATION HERE IN MILWAUKEE, 12 NEWS HAS LEARNED THAT IT ACTUALLY BEGAN WITH A DISCOVERY HUNDREDS OF MILES AWAY FROM HERE. SOURCES TELL US THAT A ROUTINE INSPECTION OF FOOD ITEMS ON STORES SHELVES IN MICHIGAN TURNED UP THE CONTAMINATION IN PRODUCTS WHICH WERE TRACED BACK TO THE MILWAUKEE PLANT. PAUL BIEDRZYCKI / MILW HEALTH DEPT - RIGHT NOW MY UNDERSTANDING IS THEY HAVEN'T IDENTIFIED A RESERVOIR SOURCE FOR THIS ORGANISM, BUT THE PLANT HAS BEEN SHUT DOWN, WHICH IS VERY APPROPRIATE. BUT NOW, THE INVESTIGATION INVOLVES MULTIPLE AGENCIES, WITH DIFFERENT RESPONSIBILITIES. RAECHELLE CLINE / DATCP - NATS... IT HAS BEEN VERY CONFUSING, EVEN FOR US. WHILE FEDERAL INVESTIGATORS, FROM BOTH THE FDA AND U-S DEPARTMENT OF AGRICULTURE, SEARCH FOR THE SOURCE OF THE PROBLEM - STATE OFFICIALS SAY THEY'RE LEFT TO WATCH AND WAIT FOR ANSWERS. RAECHELLE CLINE / DATCP - THIS IS AN INVESTIGATION DONE BY THE FDA AND THE USDA, SO IT'S REALLY NOT UNDER OUR PURVIEW AT THIS POINT. RAECHELLE CLINE / DATCP - IS IT FRUSTRATING THAT YOU CAN'T, AS AN AGENCY, STEP IN AND TAKE SOME SORT OF ACTION HERE? -- IT CAN BE FRUSTRATING BECAUSE IT IS SUCH A SERIOUS PATHOGEN. BUT WE DID WHAT WE COULD. THE STATE IS TAKING ACTION WHERE IT CAN - ENSURING THAT ALL RECALLED ITEMS ARE OUT OF STORES AND NOT AVAILABLE TO CONSUMERS. RAECHELLE CLINE / DATCP - ALL OF OUR INSPECTORS HAVE BEEN ADVISED TO LOOK FOR AND MAKE SURE THAT THESE PRODUCTS ARE NOT ON THE SHELVES. OFTEN, WHEN THERE IS A RECALL, WE TELL YOU TO GO TO OUR WEBSITE FOR MORE DETAILS. THAT'S ESPECIALLY TRUE THIS TIME - BECAUSE THERE ARE SO MANY FOOD ITEMS AND BRANDS BEING RECALLED - 16 PAGES ON THIS PRINT OUT - WE CAN'T LIST THEM ALL HERE. THE FULL LIST IS AT WISN-DOT- COM. DO WE KNOW WHERE THE INVESTIGATION STANDS OR HOW LONG IT MIGHT TAKE? NOT YET. THE F-D-A SAYS IT WON'T COMMENT BECAUSE THE INVESTIGATION IS STILL ACTIVE. A SPOKESMAN FOR THE COMPANY DID REACH OUT TO US TO SAY GARDEN-FRESH IS COOPERATING IN EVERY WAY. THE GOAL THEY SAY IS TO ENSURE SAFETY, BUT RIGHT NOW, THEY DON'T KNOW HOW LONG THAT MIGHT TAKE. THANKS. KENT. FOR THE COMPLETE LIST OF RECALLS GO TO WISN.COM